A blister package is a type of flexible packaging that is frequently used to hold small consumer goods, food, and/or pharmaceuticals (e.g., pills). Often, a thermoformed plastic web is used to form a tray having a cavity in which the item is placed, and the item is enclosed within the package either by sealing the tray to a header card (e.g., a paperboard backing) or to a flexible lidding made of plastic or aluminum foil. In still other cases, the thermoformed plastic tray is folded onto itself and/or sealed on all sides to contain the item between two portions of the web, creating a clamshell type of packaging.